The present invention relates to a light-emitting gallium nitride-based III-V group compound semiconductor device and a manufacturing method thereof, especially to a light-emitting gallium nitride-based III-V group compound semiconductor device with high resistance as well as reflection and a manufacturing method thereof.
Now scientists in various countries are dedicated to developing new LED material and improving the internal quantum efficiency of LED. However, the external quantum efficiency of LED is not improved so that there is a great difference between the external quantum efficiency and the internal quantum efficiency of LED. The reason that the external quantum efficiency of LED is not improved is in that: due to distribution of current in the p-type semiconductor layer over the active layer of the LED, photons generated from the active layer are shielded and reflected by the electrode over the p-type semiconductor layer and the photons also absorbed by the substrate of the LED. Therefore, probability of photons to be emitted from the LED is reduced.
A conventional light emitting diode includes at least a substrate, a n-type semiconductor layer over the substrate, a light emitting layer, and a p-type semiconductor layer, a first electrode disposed on one side of the substrate that is opposite to the n-type semiconductor layer and a second electrode arranged on the p-type semiconductor layer. When a voltage is applied to the LED, the current flows to the light emitting layer through the second electrode and photons are generated in the light emitting layer. Because the p-type semiconductor layer has higher resistance so that transverse current spreading in the p-type semiconductor layer is not easy. Thus most of current accumulate on bottom side of the second electrode and then when the photons generated from the light emitting layer under the second electrode are emitted from the LED, the photons are reflected by the second electrode and further absorbed by the substrate. Therefore, the external quantum efficiency of the LED is dramatically reduced. Such prior art can't meet requirements of users so that there is a need to provide a LED with high resistance and reflection for improving light emitting efficiency of LEDs.